FILM COATING METHOD USING ENGRAVING ROLLER SYSTEM

Abstract

Described is a process for film lamination, wherein an aqueous laminating adhesive is applied to a carrier film by means of a gravure roller system (direct gravure coating system), wherein the carrier film and/or an optional substrate are transparent, and the aqueous laminating adhesive comprises (a) an adhesive polymer dispersed in the aqueous phase and (b) a polyalkylene glycol dissolved in the aqueous phase, selected from polyethylene glycol and polypropylene glycol.

Claims

1.-16. (canceled)

17. A process for film lamination comprising applying an aqueous laminating adhesive to a carrier film by means of an application system, wherein the application system is a gravure roller system, wherein the carrier film to be coated moves between two rollers which rotate in the direction of the moving carrier film web, wherein one of the rollers is a gravure roller and the laminating adhesive is applied to the carrier film by the gravure roller, wherein the adhesive-coated carrier film is optionally bonded to a further substrate, wherein the carrier film and/or the optional substrate are optionally transparent or printed, wherein the aqueous laminating adhesive comprises (a) at least one adhesive polymer dispersed in the aqueous phase and (b) at least one polyalkylene glycol dissolved in the aqueous phase, selected from polyethylene glycol, polypropylene glycol and a mixture thereof.

18. The process according to claim 17, wherein the articles produced by bonding to a second substrate are selected from composite films and glossy films.

19. The process according to claim 18, wherein the articles are composite films, wherein at least two films are bonded to one another using the aqueous dispersion adhesive composition, wherein at least one film is transparent.

20. The process according to claim 17, wherein the polyalkylene glycols have a solubility in water of at least 10 g/1 at 20° C.

21. The process according to claim 17, wherein the polyethylene glycol has an average molecular weight of greater than 100 and up to 1500, and wherein the polypropylene glycol has an average molecular weight of greater than 100 and up to 2000.

22. The process according to claim 17, wherein the laminating adhesive comprises (i) from 30% to 60% by weight of the at least one adhesive polymer and (ii) from 0.25% to 3% by weight of the at least one polyalkylene glycol dissolved in the aqueous phase.

23. The process according to claim 17, wherein the adhesive polymer has a glass transition temperature of −40° C. to +15° C., measured by differential scanning calorimetry at a heating rate of 20° C./min.

24. The process according to claim 17, wherein the gravure roller is made of metal or ceramic, the second roller is a backing roller made of rubber or has a rubber surface, the web speed of the carrier film during coating with adhesive is at least 50 m/min, and the application quantity of the laminating adhesive is from 1 to 5 g/m.sup.2.

25. The process according to claim 17, wherein the adhesive polymer is selected from polyurethanes and polymers producible by free-radical emulsion polymerization of ethylenically unsaturated, free-radically polymerizable monomers comprising a) at least 60% by weight, based on the total amount of monomers, of at least one monomer selected from the group consisting of C1- to C20-alkyl acrylates, C1- to C20-alkyl methacrylates, vinyl esters of carboxylic acids comprising up to 20 carbon atoms, vinylaromatics having up to 20 carbon atoms, vinyl halides, vinyl ethers of alcohols comprising 1 to 10 carbon atoms, aliphatic hydrocarbons having 2 to 8 carbon atoms and one or two double bonds, and mixtures of these monomers, b) at least 0.1% by weight, based on the total amount of monomers, of at least one monomer having at least one acid group; c) optionally at least one further monomer distinct from the monomers a) and b).

26. The process according to claim 25, wherein the at least one monomer having at least one acid group is selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinylacetic acid, vinyllactic acid, vinylsulfonic acid, styrenesulfonic acid, acrylamidomethylpropanesulfonic acid, sulfopropyl acrylate, sulfopropyl methacrylate and mixtures of these monomers.

27. The process according to claim 17, wherein the adhesive polymer is a polyurethane constructed from a) at least one monomeric diisocyanate, b) at least one diol, of which b1) 10 to 100 mol %, based on the total amount of the diols (b), have a molecular weight of 500 to 5000 g/mol and b2) 0 to 90 mol %, based on the total amount of the diols (b), have a molecular weight of 60 to 500 g/mol, c) at least one monomer distinct from the monomers (a) and (b) having at least one isocyanate group or at least one isocyanate-reactive group which further bears at least one hydrophilic group or a potentially hydrophilic group, and d) optionally at least one further compound distinct from the monomers (a) to (c) having at least two reactive groups selected from alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups, and e) optionally at least one monofunctional compound distinct from the monomers (a) to (d) having a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group.

28. The process according to claim 27, wherein the diisocyanates a) are selected from diisocyanates of the formula X(NCO).sub.2, wherein X represents an acyclic aliphatic hydrocarbon radical having 4 to 15 carbon atoms, a cycloaliphatic hydrocarbon radical having 6 to 15 carbon atoms, an aromatic hydrocarbon radical having 6 to 15 carbon atoms or an araliphatic hydrocarbon radical having 7 to 15 carbon atoms; the diols b1) are selected from polyester diols, polycarbonate diols and polyether diols; and the compound c) is selected from dihydroxycarboxylic acids, diaminocarboxylic acids and diaminosulfonic acids.

29. The process according to claim 27, wherein the diisocyanates are selected from the group consisting of hexamethylene diisocyanate, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, 2,6-diisocyanatotoluene, 2,4-diisocyanatotoluene and tetramethylxylylene diisocyanate and a mixture thereof.

30. The process according to claim 17, wherein the adhesive polymer is a polymer producible by free-radical emulsion polymerization of ethylenically unsaturated, free-radically polymerizable monomers comprising a) 60% to 99.9% by weight, based on the total amount of monomers, of at least one monomer selected from the group consisting of C1- to C20-alkyl acrylates, C1- to C20-alkyl methacrylates, vinylaromatics having up to 20 carbon atoms, and b) 0.1% to 5% by weight, based on the total amount of monomers, of at least one monomer having at least one acid group selected from acrylic acid, methacrylic acid and itaconic acid and c) 0% to 10% by weight, based on the total amount of monomers, of further monomers distinct from the monomers a) to b), selected from the group consisting of acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, phenyloxyethylglycol mono(meth)acrylate, hydroxyl-comprising monomers, amino-comprising monomers, nitriles, alpha,beta-monoethylenically unsaturated C3-C8-carboxylic acids, bifunctional monomers which comprise not only an ethylenically unsaturated double bond but also at least one glycidyl group, oxazoline group, ureido group or ureido-analogous group, and crosslinking monomers having more than one free-radically polymerizable group.

31. The process according to claim 25, wherein the monomers a) are employed in an amount of at least 80% by weight, based on the total amount of the monomers, and are selected from the group consisting of C1- to C10-alkyl acrylates, C1- to C10-alkyl methacrylates, styrene, and a mixture thereof; and the monomers b) are employed in an amount of 0.5% to 5% by weight, based on the total amount of the monomers, and are selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid and a mixture thereof.

32. The process according to claim 17, wherein the laminating adhesive comprises at least one crosslinkable adhesive polymer dispersed in the aqueous phase and at least one reactive crosslinker.

33. The process according to claim 17, wherein the material of the carrier film is selected from the group consisting of polyethylene, oriented polypropylene, unoriented polypropylene, polyamide, polyethylene terephthalate, polyacetate, cellophane.

Description

EXAMPLES

[0142] Input Materials: [0143] Laminating adhesive A 45% aqueous polymer dispersion of a polymer composed of n-butyl acrylate, styrene and acrylic acid having a Tg of −4° C. [0144] Laminating adhesive B 45% aqueous polymer dispersion of a polymer composed of n-butylacrylate, methyl acrylate, methacrylic acid and itaconic acid having a Tg of −32° C. [0145] Loxanol® PL 5824 polypropylene glycol, molecular weight 430 g/mol (miscible with water in any ratio) [0146] Loxanol® PL 5814 polyethylene glycol, molecular weight 400 g/mol (miscible with water in any ratio) [0147] Hydropalat® WE 3162 block copolymer based on polyethylene glycol, polypropylene glycol having an average molecular weight of 2450 g/mol

Example 1

Comparison, without Additive

Laminating Adhesive A

Example 2

Comparison without Additive

Laminating Adhesive B

Example 3

Laminating Adhesive A+1% by Weight of Polypropylene Glycol (Loxanol® PL 5824)

Example 4

Laminating Adhesive B+2% by Weight of Polypropylene Glycol (Loxanol® PL 5824)

Example 5

Laminating Adhesive B+2% by Weight of Polyethylene Glycol (Loxanol® PL 5814)

Example 6

Laminating Adhesive B+1% by Weight of Polyethylene/Propylene Glycol (Hydropalat® WE 3162)

[0148] Performance Tests:

[0149] Film laminates were produced from two clear, transparent 20 μm oPP films

[0150] Application weight: 2.5-3 g/m.sup.2

[0151] Web speed: 200 m/min

[0152] Employed gravure roller: 80 lines/cm; line arrangement 45°; theoretical transfer volume 17 ml; [0153] moving in same direction as web, [0154] 200 mm diameter

[0155] Backing roller: 300 mm diameter, hard rubber coated

[0156] Laminating conditions: 6 bar linear pressure at 70° C.

[0157] The clarity of the film laminates was subjected to qualitative optical assessment.

[0158] −− poor, severe clouding and structuring visible in adhesive

[0159] +good, few defects visible

[0160] ++ very good, no defects visible

[0161] The results are summarized in Table 1.

TABLE-US-00001 TABLE 1 Visual assessment of composite film laminates Example Visual assessment 1 Without additive −− Laminating adhesive A 2 Without additive −− Laminating adhesive B 3 1% Loxanol ® PL 5824 ++ Laminating adhesive A 4 2% Loxanol PL 5824 ++ Laminating adhesive B 5 2% Loxanol PL 5814 + Laminating adhesive B 6 +1% Hydropalat WE 3162 −−